Effect of Cold Jet Plume on Aerodynamics Coefficients

Abstract

Experiments are carried out on a blunt-cone-cylinder-flare geometry to study the effect of Mach 2.65 jet plume interaction with Mach 5 freestream on overall aerodynamic coefficients. Supersonic jet plume pressure ratios P j ∕P inf of 0 to 158 are simulated, and the angle of attack α is varied from 4 to −4 deg. Flow features are captured through Schlieren and oil flow visualization. The isolation of load measuring and load nonmeasuring parts and elimination of jet reaction force are confirmed through tests. Under jet-off conditions, with an increase in the angle of attack, the flow separation on the leeward side moves toward the nose, whereas, on the windward side, the separation moves toward the base. Similar behavior is seen under jet-on conditions. However, due to jet-plume-freestream interaction, separation is more pronounced on the leeward side. In general, as P j ∕P inf increases, the aerodynamic coefficients decrease irrespective of angles of attack. At the maximum P j ∕P inf of 158, C N , C m , and C A are decreased by 15, 22, and 30%, respectively. Also X CP moves toward the nose by 1.15D, 0.6D, and 0.25D for α 1, 2, and 4 deg, respectively.= pitching moment about nose NF = normal force, N P = static pressure, bar P inf = freestream static pressure, bar P j = jet static pressure, bar P j ∕P inf = jet pressure ratio P 0j = jet nozzle pressure, bar P 0 = total pressure, bar P 01 = tunnel stagnation pressure, bar P 02 = total pressure behind normal shock, bar Re = Reynolds number SF = side force, N S ref = reference area, mm 2 T = static temperature, K T 0 = total temperature, K T 01 = tunnel stagnation temperature, K V ∞ = freestream velocity, m∕s X = coordinate system X CP = center of pressure Y = coordinate system Z = coordinate system α = angle of attack γ = Specific heat ratio ρ ∞ = freestream density, kg∕m 3 ∞ = freestream